modifying the D1 I/V stage (X?, CCS?)

Single DAC use

Is it possible to use this I/V converter with just one DAC instead of two? For example by grounding the input of Q6. Will it work?

You could remove Q6 and all the circuitry around it.

Brian,

You could get rid of R25 and R32 and replace them with 20ml current sources. With Mr.Pass's permission.

Regards,
Jam

Check the DC output requirements of the chip, but otherwise,
ther answer is (should be) no problem.

In reference to the above schematic, I should point out that
the followers are not necessary for many applications, and you
could get by with the simple diff pair and the 1.5K resistors
(capacitively coupled, of course).

conversion to 0,1mA DAC?

Hi,

I have also released a question about converting the D1 stage, maybe in the wrong forum part, because just one answers has come so far...

The essence of the tread below is: how to use the 0,1mA I-output of TDA1547 with a changed D1-stage? My idea is the reducing of bias current to ca. 1mA and use of a smaller FET like e.g. 2SK389. Is there any mistake in this realization? Thanks for feedback!

http://www.diyaudio.com/forums/showthread.php?threadid=19751

Regards

Klaus

It seems that current output DACs are designed to
ideally operate into virtual grounds.

As the transconductance of the JFET in question goes
down, more signal voltage will appear at the source,
and any dependence of signal quality vs output voltage
of the DAC will start showing up.

That said, I would expect it to work fine.

why does the output use such a high capacitor?
If I feed one ouput into the balanced line stage could I use 10-22uF MKP cap?

Hi Klaus,

I want to upgrade my Marantz CD 16 with the 1547 inside as well. So, I would be extremly interested to understand if you succeed in combining a 1547 with Nelson's D1-stage and basiscally what the final schematic was / how you connected it to the 1547.

Thanks & Best Regards

Ouput Cap ?

I would like as well to ask the same question as promitheus: Why is the Output cap so large ?

Which impedance does it see ? If it sees the 22K only, than 1 uF would be sufficient. If it sees only the 150 R, 212uF would be required for 5 Hz. Sorry, that's a newbie question, but before I start to spend long time with books, I want to ask the designer pros here.

Anyway, I would prefer to understand how I could get rid of the cap anyway ?

Re: Ouput Cap ?

Blitz said:

Anyway, I would prefer to understand how I could get rid of the cap anyway ?

Click to expand...

To get rid of the cap you would need a servo.

would a DC Servo circuit be bad for reproduction quality or not?
LCAudio uses two of them in there DAC I/V stage.

promitheus said:

would a DC Servo circuit be bad for reproduction quality or not?
LCAudio uses two of them in there DAC I/V stage.

Click to expand...

The only true way to judge would be to build and listen.

TDA 1541 with D1 output stage

Has anyone tried the D1 output stage in combination with the
TDA 1541, SAA 7220B? (4mA output)
How about de-emphasis filter?

Re: TDA 1541 with D1 output stage

PAM said:

How about de-emphasis filter?

Click to expand...

Is this a big issue?

De-emphasis

Sheffield Lab CD's use de-emphasis. so I need it.
- James Newton Howard and friends
- Michel Ruff's Speaking in melodies
are CD's I like very much.

Re: De-emphasis

PAM said:

Sheffield Lab CD's use de-emphasis. so I need it.
- James Newton Howard and friends
- Michel Ruff's Speaking in melodies
are CD's I like very much.

Click to expand...

How can I test if some of my CDs are amphased?